This invention relates to miniaturized devices for the controlled exposure or release of molecules such as drugs and/or secondary devices such as sensors.
U.S. Pat. No. 5,797,898 to Santini, et al. describes active or passive microchips for the delivery, i.e. release, of molecules such as drugs. These microchip devices contain reservoirs filled with the molecules to be released. In some embodiments, the reservoir openings must be sealed, after they are filled, to prevent leakage from or between any of the reservoirs. The ""898 patent discloses that the reservoirs can be sealed, for example, with a waterproof epoxy or other material impervious to any fluids surrounding the device. It is important to avoid contacting the drug or other reservoir contents with the chemical adhesive. The use of such chemical adhesives may necessitate additional testing to determine the presence and nature of any interactions between the chemical adhesive and each drug or other chemical to be released. Furthermore, chemical adhesives may require long times, high temperatures, and/or exposure to ultraviolet light in order to cure completely. These curing processes, however, may degrade sensitive chemicals or drugs in the reservoir. It therefore would be advantageous to provide additional methods of sealing the device which do not require the use of chemical adhesives, or if used prevent contact between the adhesives and reservoir contents.
It is therefore an object of the present invention to provide devices and methods for sealing the reservoirs of microchip devices for the controlled release of drugs and other molecules, which do not require the use of chemical adhesives or sealants, or which prevent contact between the reservoir contents and the adhesives.
These and other objects, features, and advantages of the present invention will become apparent upon review of the following detailed description of the invention taken in conjunction with the drawings and the appended claims.
Methods and devices are provided for sealing the reservoirs of microchip devices to prevent leakage from or between any of the reservoirs. The methods advantageously prevent contact between the reservoir contents (e.g., molecules such as drugs and reagents or smaller devices such as sensing components) and chemical adhesives, if any, used in the sealing process. In a preferred embodiment, the sealing method comprises (i) providing a microchip device having a front side and a back side, wherein the back side has a plurality of reservoir openings in need of sealing; (ii) positioning a gasket material, such as a flexible polymeric sheet, over the reservoir openings; and (iii) securing one or more backplates over the gasket material to compress the gasket material to the back side of the microchip device so as to seal the reservoir openings. A barrier layer, such as polyethylene glycol, may be applied into/onto the reservoirs/substrate to provide a barrier between the reservoir contents and the sealing system.
Preferably, the backplate is secured by mechanical means; however, where a chemical adhesive is used in place or in conjunction with mechanical means, the gasket material is interposed between the reservoir openings and the chemical adhesive. In one embodiment, the mechanical means comprises securing the microchip device and the gasket material between a front sealing frame and the backplate. Mechanical securing means for attaching the backplate to the substrate of the microchip device or to the front sealing frame include the use of fasteners, crimping, pins/holes, soldering, and welding.
In another embodiment, the sealing method comprises (i) providing a microchip device having a front side and a back side, wherein the back side has a plurality of reservoir openings in need of sealing; and (ii) securing one or more composite backplates to the backside of the microchip device. The composite backplate includes one or more sealing plugs which seal the reservoir openings. The composite backplates also preferably are secured by mechanical means, although a chemical adhesive can be used where the sealing plugs are interposed between the reservoir openings and the chemical adhesive. In one embodiment, the composite backplate comprises a rigid substrate having a plurality of sealing plugs extending therefrom, such that the sealing plugs are aligned with and project, at least partially, into the reservoir openings. The sealing plugs can comprise a plurality of wells, which can contain the molecules or devices for introduction into the reservoirs of the microchip during the securing of the composite backplates.
The microchip devices sealed with these methods typically include reservoir caps useful in the controlled release and exposure of the molecules and devices contained therein. The methods include the steps of providing the microchip device at a site where the molecules or devices are to be delivered, and then controlling the release or exposure of the molecules or devices from the reservoir by diffusion through or disintegration of the reservoir cap.